From: Rabbi Moshe Sofer
To: Unknown recipient
Three partners jointly purchased gems; one partner (Shimon) took custody of them and later claimed they fell out of a torn pocket. The Chasam Sofer rules that Shimon must swear a solemn oath and pay the full market value of the lost gems, as he bore the status of a shomer sachar by virtue of the benefit he derived from holding them, and his storage method was close to negligence. The ruling extensively defends the Rema's position against the Shach, demonstrating that willing partners bear guardianship obligations and that shmirah b'ba'alim does not apply to ordinary partnerships.
Source: Shu"t Chasam Sofer CM §97